11.1 Corporate Mergers

Antitrust Laws and Corporate Mergers

Purpose of Antitrust Laws

Antitrust laws exist to promote competition and prevent monopolies from forming or abusing market power. When companies want to merge, these laws require government review to make sure the deal won't harm consumers through higher prices, lower quality, or reduced innovation.

Three foundational laws form the backbone of U.S. antitrust policy:

• Sherman Act (1890) prohibits anticompetitive agreements (like price fixing between competitors) and attempts to monopolize a market
• Clayton Act (1914) targets specific practices, including mergers and acquisitions that may substantially lessen competition
• Federal Trade Commission Act (1914) established the FTC as the agency responsible for enforcing antitrust laws and protecting consumers

The Hart-Scott-Rodino Act (1976) added a practical enforcement mechanism: companies proposing mergers above a certain dollar threshold must notify antitrust authorities before completing the deal. This gives regulators time to investigate. If a merger would significantly reduce competition, authorities can block it entirely. For example, the proposed AT&T and T-Mobile merger was blocked in 2011 because regulators determined it would concentrate too much of the wireless market in one company.

Types of Corporate Mergers

Not all mergers raise the same concerns. The type of merger matters for how regulators evaluate it:

• Horizontal merger: Two companies in the same industry at the same stage of production combine. This is the type most likely to raise antitrust red flags because it directly reduces the number of competitors. Think of two major airlines merging.
• Vertical merger: Companies at different stages of production or distribution in the same industry combine. A car manufacturer buying a tire supplier would be vertical integration. These can raise concerns about foreclosing competitors from key inputs or distribution channels.
• Conglomerate merger: Firms in unrelated industries combine. A tech company acquiring a food brand, for instance. These rarely trigger antitrust concerns since the firms don't compete with each other.

Mergers can also produce real benefits:

• Synergy: The combined entity operates more effectively than the two firms did separately
• Economies of scale: Larger production volume can lower per-unit costs, potentially benefiting consumers through lower prices

Measuring Market Concentration

Concentration Ratios

Before regulators can decide whether a merger is harmful, they need to measure how concentrated a market already is. Concentration ratios do this by adding up the market shares of the largest firms in an industry.

• Four-firm concentration ratio (CR4) sums the market shares of the four largest firms. The U.S. chocolate market, dominated by Hershey, Mars, Nestlé, and Ferrero, has a high CR4.
• Eight-firm concentration ratio (CR8) does the same for the top eight firms.

To calculate a concentration ratio:

1. Define the relevant market (e.g., the U.S. smartphone market)
2. Identify the largest firms (Apple, Samsung, Motorola, etc.)
3. Calculate each firm's market share as a percentage of total industry sales
4. Sum the shares of the top four (for CR4) or top eight (for CR8)

Concentration ratios are simple and intuitive, but they have a limitation: they don't tell you how market share is distributed among those top firms. That's where the HHI comes in.

Herfindahl-Hirschman Index (HHI)

The Herfindahl-Hirschman Index gives a more complete picture of market concentration because it accounts for the relative size of all firms, not just the top few. Squaring each firm's market share means that firms with very large shares contribute disproportionately to the index, which reflects their outsized market power.

To calculate the HHI:

1. Define the relevant market (e.g., the U.S. ride-sharing market) and identify all firms (Uber, Lyft, Via, etc.)
2. Calculate each firm's market share as a percentage of total industry sales
3. Square each firm's market share
4. Sum all the squared values

$HHI = \sum_{i=1}^{n} (S_i)^2$

where $S_i$ is each firm's market share expressed as a whole number (e.g., 40 for 40%).

HHI and merger review: Antitrust authorities at the DOJ and FTC use the HHI to evaluate proposed mergers. A merger that would increase the HHI by more than 200 points in an already concentrated market (above 2,500) raises serious antitrust concerns and is likely to face a challenge.

Approaches to Merger Regulation

When regulators review a proposed merger, they have several tools at their disposal:

Premerger notification under the Hart-Scott-Rodino Act requires companies to file with antitrust authorities before completing mergers above a specified size threshold. Authorities then review the deal and can challenge or block it if they find likely anticompetitive effects.

Behavioral remedies allow a merger to proceed but attach conditions designed to prevent harm to competition. The merged firm might be required to license technology to rivals or agree to specific business practices. The Ticketmaster and Live Nation merger, for example, was approved with behavioral conditions meant to prevent the combined company from using its dominance to shut out competitors.

Structural remedies require the merging firms to sell off certain assets or business units so that a viable competitor remains in the market. When Anheuser-Busch InBev acquired SABMiller, regulators required divestitures to preserve competition in the beer industry.

Enforcement through litigation is the final option. Antitrust authorities can file lawsuits to block mergers they believe violate the law. Courts evaluate these cases using the rule of reason approach, weighing the merger's likely effects on competition and consumer welfare rather than declaring it illegal on its face.